When multicrew first came out, I hosted a couple of stranger guests and we tried to do a mission after we landed and disappointedly found out the SRV was redded out, even if it was just me wanting to use it.
I'm guessing a technical hurdle could be that the state of the ship is different when left behind using the SRV where perhaps there was a lot more needed to get it to work without massive bugs and could not be finished before the 2.3.0 release date.
Like what would happen if the host in the SRV with multicrew players still in the mc seats, dismissed the ship? In non-mc, the ship dismissed seems to warp out into supercruise and leave the instance entirely like an npc ship. if the mc guests were still on the ship, would it mean they could be set to orbiting sc with rudimentary autopilot while an SRV was down on the surface, an ability that doesn't exist in the game yet where a fighter crew or mc player can't be sent out on the SRV in the first place. They could red out the ability to dismiss but then it would not make sense when the ability to dismiss works without mc. In mc off a planet, the host still can't leave the ship in a SLF when in a mc session where in non-mc, the mother ship is left in an npc like state where the fighter npc crewmember can take over the ship, but then I guess the npc taking over the ship from the main cockpit view mode hasn't been implemented where in mc session, the mc guests would have to be witness to the npc flying the ship from their perspectives. Overall, signs of a bunch of more perplexing coding issues that would need to be solved.